1. Field of the Invention
The invention relates to a guiding device, more particularly to a drill bit guiding device which is used to guide the formation of holes in a wooden workpiece.
2. Description of the Related Art
Drill bit guiding devices are used when it is desired to form holes in a wooden workpiece accurately. Referring to FIG. 1, a conventional drill bit guiding device 1 includes a substantially U-shaped member with two spaced parallel portions 101, 105 and a connecting portion 102 which integrally interconnects the parallel portions 101, 105. The parallel portion 101 is formed with three threaded through-holes 103 and three indicating lines 107, while the connecting portion 102 is also formed with three threaded through-holes 103 which correspond respectively to the through-holes 103 of the parallel portion 101. The parallel portion 105 is provided with a retaining bolt 106 which passes threadedly therethrough. Each of the threaded through-holes 103 receives removably a tubular guide wall 104 therein to prevent damage to the threaded through-holes 103 during the boring operation of holes through the wooden workpiece.
Referring to FIG. 2, when it is desired to bore a hole A2 through a side surface A1 or a hole A3 adjacent to the side surface A1 of a wooden workpiece (A), the workpiece (A) is placed below the parallel portion 101 of the conventional guiding device 1 with the surface A1 abutting against the connecting portion 102. The retaining bolt 106 is rotated inwardly so as to clamp the workpiece (A). A drill bit (not shown) is inserted axially of the tubular guide wall 104 as shown by the arrow F1 or F2, thereby forming the hole A2 or A3 in the workpiece (A).
When it is to form a hole A2 or A3 in another workpiece to permit connection with the former workpiece by means of dowel pin, an indicating line which is aligned with one of the indicating lines 107 on the parallel portion 101 must be drawn on the surface A4 of said another workpiece.
Note that only one workpiece can be drilled at one time the conventional drill bit guiding device 1 is in use. Since the indicating line on the surface A4 of said another workpiece is drawn manually after boring the hole A2 in the former workpiece, the indicating line on said another workpiece may be mis-aligned with the axis of the hole A2 of the former workpiece, thereby resulting in an improper connection between two workpieces when the latter are connected to each other by means of the dowel pin.
FIG. 3 shows another conventional drill bit guiding device 5 which includes two parallel portions 204, a connecting portion 206 which interconnects the parallel portions 204 and a protrusion 201 which extends from the connecting portion 206 in the same direction as the parallel portions 204. Each of the parallel portions 204 is provided with a retaining bolt 205 which passes threadedly and perpendicularly therethrough. The connecting portion 206 is provided with a plurality of through-holes 202 which receive a respective tubular guide wall 203 therein. The conventional drill bit guiding device 5 can clamp two workpieces (A) at one time so that holes A2 can be bored through the side surface A1 of the workpieces A. The conventional drill bit guiding device 5, however, cannot be used to bore holes adjacent to the side surface A1.